Parenteral selenium supplementation in extremely low birth weight infants: inadequate dosage but no correlation with hypothyroidism.

Abstract

Selenium is an essential trace element, known to be important in thyroid metabolism. We speculated that parenteral selenium supplementation is inadequate in preterm infants and may contribute to the development of hypothyroidism. Serum selenium and thyroid function were evaluated on day 10 of life in extremely low birth weight infants. Selenium intake provided by parenteral nutrition was prospectively evaluated. Selenium intake was close to the recommended 2 micrograms/kg per day. Serum selenium values were 0.54 +/- 0.13 microM (mean +/- SD, n = 29). Selenium serum levels were low in 26 of 29 infants. In infants with subnormal serum selenium levels, free T4 was transiently low in 10 of 26 infants but was normal in 16 of 26 infants. No significant correlation was found between serum selenium levels and hypothyroidism. Current selenium supplementation guidelines may be inadequate in extremely low birth weight infants. However, selenium deficiency does not seem to play a major role in neonatal hypothyroidism.